Methods of manufacture of compressor blades



Nov. 14, 1961 I w. w. FRANK 3,008,223

METHODS OF MANUFACTURE OF COMPRESSOR BLADES Filed Sept. 29, 1955 3 Sheets-Sheet 1 "I 1' a HI INVENTOR WILEERT w. FRANK METHODS OF MANUFACTURE OF COMPRESSOR BLADES Filed Sept. 29, 1955 W. W. FRANK Nov. 14, 1961 5 SheetS-I-Sheet 2 wL f n I w! 0 0. e a W I W ZIHMII q In z w lum 3 ulwwl l H M INVENTOR 51?- 5 WILEERT w. FRANK BY )6 Z A ORNE W. W. FRANK Nov. 14, 1961 METHODS OF MANUFACTURE OF COMPRESSOR BLADES Filed Sept. 29, 1955 '3 Sheets-Sheet 3 EEEILIENIZINE DIAGRAM IRETRAD'IHIJLDIADVANE FEED RAM 4 3 ADVANCE HULD ELAMPED TUEIE ELAMP401 ELAMF'ED TUBE HEATER 6 6 ELEIEEI HDLD ||:l.usr;| HIJLD FDRM DIE {9J0 VENT BUTTER-6'6 CUT- EFF VIS E- 67 ELIT-EIFF WHEELE Z576 INVENTOR WILBER'I' \N. FRANK mg 3 a A RNE United States Patent 3,008,223 METHODS OF MANUFACTURE OF COMPRESSOR BLADES I Wilbert W. Frank, Long Valley, N.J., assignor to Curtiss- Wright Corporation, a corporation of Delaware Filed Sept. 29, 1955, Ser. No. 537,451 12 Claims. (Cl. 29-156 .8)

This invention concerns the fabrication of hollow metal articles by die-forming. It is concerned in particular with the manufacture of hollow compressor blades of airfoil cross-section from seamless tubing, and with methods and machinery for rapid production of such blades. The novel methods and equipment developed for compressor blade production are readily adaptable to the fabrication of other sorts of end products. While this specification emphasizes compressor blades, the scope of the invention encompasses other analogous articles.

My invention, briefly, consists of the following procedures:

Random lengths of seamless tube stock are fed, one by one and in an direction, into the forming equipment. The only preparation for the tubes, is a swaging of one end of each so that a following tube is engaged with the end of a tube which is active in the equipment. The free end of the active tube, or of the following tube, is sealing chucked to a compressed gas supply, so that the tubes are internally pressurized. The active tube is progressively fed into a die set, Which has spaced flattening or crimping dies. These engage part of the tube, flattening spaced parts thereof to confine gas pressure in the tube section therebetween. Forming dies then engage this section to form it to compressor blade configuration. After the forming dies have dwelt closed for a brief interval, the formed section is pierced to vent gas pressure therefrom. The dies are opened and the formed section is advanced to a cutoff station on the equipment, whereat the formed compressor blade section is cut away from the crimped parts of the tube stock.

The crimp on the downstream end of the die remains on the tube stock to confine gas in the tube stock for the next die pressing sequence. The several steps in the process are all sequence-controlled by appropriate timing apparatus, whereby a substantially continuous production of blades or articles ensues.

Reference may be made to the annexed drawings and the following detailed description for a more comprehen: sive explanation of the invention and of various ramifications thereof.

Objectives of the invention are; to provide a high-production, simple mode of compressor blade manufacture, whereby highly precise blades may be fabricated at nominal cost; to provide a method of dieforming hollow articles from thin tubing; to provide a continuous method of gas pressurizing the interior of thin tubing during dieforming operations; to provide a technique for venting gas pressure from a hollow formed article to prevent subsequent distortion thereof; and to provide means to produce formed finished hollow articles on a continuous cyclic basis, including preheating, if necessary, forming and trimming.

In the annexed drawings, in which similar reference characters designate similar parts,

FIG. 1 is a side elevation of the principal parts of a machine for producing hollow articles, according to the invention; H

FIG. 2 is a longitudinal section through part of a the set used in the FIG. 1 machine, and is a section on the line 22 of FIG. 5;

FIG. 3 is an end elevation of the die set on the line 3-3 of FIG. 2; a

3,008,223 Patented Nov. 14, 1961' FIG. 3, with FIG. 7 is a section through forming dies on the line 7-7 of FIG. 2;

FIG. 8 is a perspective elevation of a finished product of the machine;

FIG. 9 is a section through part of the lower forming die and slitter on the line 9-9 of FIG. 5; and

FIG. 10 is a periodic sequencing diagram of the several components of the FIG. lmachine.

Reference may first be made to FIG. 1 wherein the upper part of the figure shows feed mechanism for raw tube stock 12, and the lower part of the figure (which in the actual machine is a rightward prolongation of the mechanism of the upper part) shows the several work stations which convert tube stock into finished hollow compressor blades 14 as shown in FIG. 8.

The feed mechanism comprises guide rails 16 and 17' supported by a rightward post 18 and a leftward post, not shown. The rails 16 and 17 guide a slide 19 whose upper end carries a pressure nozzle and tube pusher 20, this nozzle being fed with pressurized gas through a pipe 21 from a supply source not shown. The slide 19 is connected to a rod 22 of a device, not shown, which usually exerts rightward force on the slide, to hold the nozzle 20 engaged with the left .end (as shown) of the tube stock 12. The tube is supported by guide rolls 23 supported on a table 24 so the tube may move linearly on a path parallel to its own axis. 1

The tube is moved rightwardly, as will be described, into the forming stations of the machine, and as it moves, the slide 19 follows it, the nozzle 20 engaging the tube end and maintaining the tube interior under gas pressure. As a length of tube stock is used up, the slide 19 approaches the post 18, whereupon the top of the slide engages a limit switch 26. This switch actuates a mechanism not shown, and not forming an intergral part of the invention claimed herein, which retracts the slide 19, installs a fresh piece of tube stock on the rolls 23, engages the nozzle 20 with the left end of the new tube, and engages the right end of the new tube with the-left end of the old tube.

The pieces of tube stock are all preformed at their right ends to substantially the same conical shape as that of the nozzle 20, so they Will center on the old tubes 12 in the machine, and will make a gas-tight joint therewith. Thereby, tube feed is substantially continuous, and gas pressure is transferred to those parts of the tube stock which are being formed in the right-hand end of the machine.

Tube stock 12 moves into a feed station comprising a fixed post 28 carrying a lower guide roll 29 and an upper guide roll 30, the latter being spring-pressed at 31 to en-, gage the tube stock. The post 28 carries guide rails 32 and 33, supported at their right ends in a fixed post 34.

Guided on rails 32 and 33 is a slide 36 which carries, at its upper end, a tube clamp. or vise 37, comprising a' lower fixed jaw 38 and an upper movable jaw 39, the latter being movable to engage or release from tube 12 passing therethrough by means of a tube clamp motor 40. The latter is operated to open or to clamp the 3 7 determines the increment of tube stock fed to the machine for each operating cycle.

Tube stock 12, as it is advanced rightwardly in the machine, passes through an induction heating coil 46,

failure of the metal. Where the tube stock is annealed and thin-Walled, heating may be'unn'ecessary, in which case the tube heater 46 may be omitted from the machine.

Rightward of the feeding and heating stations, a forming press and diesel are located, through which the tube stock passes its rightward movement. The press bed is shown at 49, and the vertically movable press ram at 50. These elements may form part of a conventional power operated press, either mechanically, hydraulically or pneumatically operated. Between the bed and ram, adie set 51 is disposed, by which tube forming is accomplished. As will be described in detail later in connection with other figures, the die set is double-acting, first crimping or flattening spaced-apart portions of the tube stock as at 52 and 53, then forming the intervening portion 5401. the stock. The crimping at 52 and 53 seals the portion .54 from escape of pressurized gas therein, so that when the forming dies close, they close not only against the resistance of the tube material, but against the gas pressure. The internal gas pressure holds the tube walls in intimate contact with the forming die faces.

When the forming dies are fully closed, the internal gas pressure, increased several fold from line gas pressure due to reduction in internal volume of the tube portion 53.,--enforces precise conformation of the tube walls to the forming die cavity shapes. 7

Prior to opening of the forming dies, it :is necessary to relieve the high internal gas pressure from the formed portion '54 between crimps 52 and, 53. If this were not done, :gas pressure would expand and distort the portion 54 upon die opening. I'provide a cutter 55 movable in the die set which is operated by a suitably sequenced motor :56 (FIGS. and 9) and which pierces the formed workpiece portion 54 to provide a vent for the escape of gas. a

After piercing the dies open and the formed workpiece increment 52, 53, 54 is advanced from the dies by the feed ram '43, to a position where the crimp 52 occupies the same location that the crimp 53 previously occupied. This crimp holds the tube end closed and prevents the escape of gas pressure during advance of the tube stock.

Formed tube increments 58 and 60 are shown in FIG. 1, advanced to the right of the die set 51. At the station occupied by one of these increments, 60 as'shown,

cut olf equipment is arranged. 'This equipment includes a fixed support 62 having support components 63, 64

: and 65 which engage lower faces, as shown, of the formed. tube increments. A power operated clamping 'vise 67' is arranged adjacent the support 62, including jaws 68 and 69 whichare sequentiallyengaged with upper surfiaces of the tube increment '60, opposite the support components 64 and 65. By this arrangement, the tube -in-' crement is firmly held attimcs to enable cutting off or trimming of the finished compressor blade (14 in FIG,

8) from the formed tube increment.

Cutting'ofi is accomplished by cutoff wheels 71 and 72 journalled in movable bearing arms 73 and 74. The wheels are driven by conventional'means, and the arms 73 and 74 are periodically swung, as by motor units 75 and 76 to engage the wheels ,with the formed tube'increment, sever the blade 14' from the stocleand retract the wheels to allow the next advance of the stock. The wheels 71 and 72*are spaced to finish the blade to the desired length, I andthe sarms Band 74 are swung on axes, or, moved on slides, to cut the stockv on any desired angle. For instance, shown in a plane normal to the stock axis, While the wheel operation.

in FIG. 1 the wheel 71 is 72 is shown tilted relative to the stock axis to produce an angled cut. p

The support portion 63 holds the outboard part of the tube stock while cutting by the wheel 71 is effected, to prevent bending or distortion of thestock disposed between the die set 51 and the cutofi vise.

Aftercutofi and release of the stock the finished blades 14 are cleared from the machine, and the stock scrap beyond a clamped blade, as represented at 78, is also cleared, readying the machine for the next cycle of Reference may now be made to FIGS. 2-7 wherein the details of construction of the die set 51 are shown.

The die set comprises a bottom plate '86 having four corner posts 82 rising therefrom. A top plate 84 is fitted to the posts 82 and is slidable vertically thereon. On'the plate 80 a bottom forming die 86 is secured as by screws 88, and to the top plate, 84 an upper forming die 90 is secured as by screws 92. A cover plate 94 is secured by screws to the top plate 84 to provide adequate clearance betweenthe press bed and the press ram, between which the die set is disposed, to avoid the corner posts 82. projecting through the top die when the die set is closed. The upper face of the lower die 86 is provided with a forming cavity 96, and the lower face of the top die 98 is provided with a forming cavity FIG. 7 shows a section through the dies 86 and 90 and the configuration of the cavities 96 and 98. To

' provide the precise location of the tube stock between the dies, the lower cavity 96 is sunk beneath the top face of the die, and the cavity 98 is formed on a downward extension from the upper die 90. -When the dies are open the tube rests in the recess of the lower die and as the upper die is closed it presses the tube downwardly into the lower die recess and forms it in the desired manner. In order to carve the lower die .face 96, edgewise clearance is required and the clearance is taken up by the insertion of supplementary blocks 100 on either side of the die cavity 96.

At each end of the die set, crimping dies are located.

Referring to FIG. 2, a lower left crimping die plate 102 carries a crimping anvil 104, and an upper left crimping die plate 106 carries a crimping tool 108. Both die plates 102 and 108 engage the end posts 82 through ears 107 and 109 respectively to guide them in their vertical sliding. .The die plate 102 is urged upwardly by stiff springs 110 embracing posts 82 and engaging ears 107 which raise the anvil 104 when the die set is open, to substantially the same level as the lower die cavity 96. Lighter springs 1'12 piloted on the posts 82 are located between the ears 107 of the lower die plate 102'and ears 109 of the upper die plate 106, to hold them apart when the, die set is open. Additional stiff springs 114 embracing the posts 82 are disposed between the upper die block 84 and the ears 109 of the die plate 106 to hold the crimping tool 108 below the level of the upper die cavity 98 when the die set is open;

Assuming'there is tube stock located across the die openings, and that the die setis open as shown in FIG. 4, lowering of the press ram toward the press bed has the following elfect. Initial movement of the die block 84 is downward toward the die block 80 and the stiff springs 114 and 110 force the crimping tool 108 toward the crimping anvil 104 and flatten the tube stock between them prior to engagement of the die cavities 96 and 98 with the tube surface. The springs 110 and 114 are stifi enough or may be pre-loaded so that complete flattening or crimping of the tube stock is accomplished before engagement of the forming dies with the tube.

It will be recalled that the interior of the tube is .exposed to high gas pressure. When the crimping takes place, this gas pressure is locked within that part 54 of the tube stock between the two sets of crimping tools, preventing escape of the gas.

After die blocks 80 and 84 are moved further toward one another, the crimping tools are bottomed onone another, the springs 110 and 114 yield, and the dies 86 and 90 engage the tube stock and flatten it and form it in conformity with the shape of the die cavities. During this flattening, since gas pressure is confined within the tube stock being worked on, gas pressure is raised to a level several times greater than the original gas pressure, due to the reduction in volume of the interior of the tube stock. This high gas pressure minimizes any tendency for the thin wall tube stock to crease or buckle as die forming takes place, assuring a formed product which is true to the form of the die cavity.

Additional components of the die set to assure precise and smooth operation, include U shaped guides 118 at each end of the die set and secured to the die plates 10-2, whereby the tube stock is held centered as it passes along through the die set. Also, the die plate 84 is provided with books 120 which engage bars 122 secured to die plates 106, so that when the die set is opened, the downward movement of plate 106 is limited relative to the plate 84, to fully enable full opening of the crimping tools for feeding of tube stock through the die set.

FIG. 6 shows the relationship of the crimping anvil 104 and the crimping .tool 108. When the crimping tools are fully closed they are designed with a clearance 124 which is equal to twice the wall thickness of the tube stock less a small allowance for compression of the tube stock to assure a tight seal when the tube is flattened.

FIGS. and 9 show the vent slitter 55 and its motor 56 which were referred to previously. As will be seen in FIG. 9, the lower die 86 is formed with a transverse groove 126 along which the vent slitter 55 is slidable. The slitter comprises a tool-steel strip formed with a sharpened corner 12.8 which normally is out of engagement with tube stock confined between the dies. When the proper time interval occurs for venting the tube stock, the slitter 55 is moved to the right by motor 56 whereupon the point 128 engages the confined tube stock and pierces it. Leftward movement of the slitter opens the thus formed vent permitting the escape of the high-pressure gas contained within the formed tube stock.

From the foregoing description, it will be noted that there are several motor devices; namely, the feed ram 43, the tube clamp motor 40, the tube heater 46, the die set 51, the vent slittter motor 56, the cutofi vise motor 67 and the cutofi wheel swinging motors 75 and 76 which must be operated periodically and in a precise sequence to accomplish the objectives for which the equipment is designed. FIG. 10 shows a typical sequencing'diagram wherein the several motors are listed on the left side of the figure and wherein their operation times are designated in a horizontal direction between the beginning and end of a complete operating cycle designated by the lines 0 and T. Such cycle may be a few seconds, possibly up to around one minute, depending upon the time required for accomplishment of the different operations performed by the machine.

Possibly the greatest time intervals are those which are required to cut olf the tube stock, and required to efiect a complete forming of the tube stock between the forming dies. These intervals are represented by the areas labelled Hold and Cut for the respective functions. The other operations of opening, clamping, retracting, and advancing the several motors are shown in relation to the Hold and Cut intervals of the forming die and cutoif wheels. The opening and closing operations of the different components of the machine may be accomplished in very brief time intervals. The time required to advance stock in the machine by operation of the feed ram 43 takes only a very short time interval since there is no substantial load resisting the advance movement. It will be noted in the sequencing diagram that the forming of the tube stock by the dies and the cutting off of a formed piece of tube stock may be accomplished concurrently. The vent slitting and retracting of the vent slitter occurs while the forming die is at the last part of its closure, just prior to die opening. This enables maximum time dwell for the forming of the tube stock between the forming dies.

The proper sequencing, according to FIG. 10, is accomplished by commercially available timing and sequencing equipment, usually of electrical character though not necessarily. If electrical sequencing equipment is used, the switches thereof actuate commercially available solenoid valves where the motors to be operated are hydraulic or pneumatic. It is considered that the arrangements needed to attain, the desired functions are wtihin the scope of those skilled in the art.

Multiple fixed interval repeat timers are typified by the series 5800 timers made by Haydon Mfg. 00., Inc., Torrington, Conn, or Types CF3, CF6 or M made by the R. W. Cramer Co., Inc., Centerbrook, Conn. These comprise a motor driven shaft carrying a plurality of cams, whose lobes are adjustable in length and actuate on-ofi switches forming part of the assembly. By proper selection of such catalog equipment, the time intervals and sequence required, as shown in FIG. 10, may readily be secured. The circuits controlled by the timer mechanism. are connected to operate solenoid valves which control pressurized fluid flow to and from the fluid motors such as 43, 40, press 49, 50, 56, 67 and 75, 76. Such solenoid valves are readily available catalog items, and are typified by those made by the Automatic Switch Co. of Orange, N.J., Magnetrol Valve Corp. of Hawthorne, NJ., and R. G. Laurence Co. of Tenafiy, NJ. 7

It will be clear to those familiar with equipment of this sort that the scheduling of events in the operating cycle of the machine may be varied widely and that different locations and arrangements of the several components of the machine may be made according to the tube forming problem being dealt with. In general, the machine as described is sufiiciently flexible to accommodate tube stock of d-iiferent wall thicknesses andlengths' so that a variety of difierent formed end products may be produced from the same basic machine without extensive modification. When different end products are to be produced, the only major change is in the die set 51. It is contemplated that a different die set be made available for each difierent type of end product to be produced from the machine. Even so, with the same die set compressor blades of the type shown in FIG. 8 may be made in several lengths, using the same die set, merely by modifying the distance between the cut-off wheels 71 and72.

Though one embodiment illustrating the invention has been illustrated and described, it is to be understood that the invention may be applied in various forms. Changes may be made in the arrangements shown without departing from the spirit or scope of the invention as will be apparent to those skilled in the art. Reference should be made to the appended claims for a definition of the limits of the invention.

I claim:

1. The method of making a hollow metallic blade of airfoil cross section which consists in closing one end of a tubular workpiece, mechanically advancing the closed tube end through a forming die, applying gas pressure to the inside of the workpiece from its open end, closing the forming die upon said workpiece near its closed end, concurrently pinching to substantial flatness the workpiece at each end of the workpiece section to hold gas pressure therein during forming die closure, opening the forming die and relieving gas pressure from the formed and pinched workpiece part, advancing the die formed and pinched workpiece part out of said forming die, and

cutting off the formed part of said workpiece inwardly V of the pinched lends thereof. V V v M I .2. The method of makingna hollow blade of airfoil cross section from' a long .hollow, tubular blank which consists in pressurizing the interior of said blank, PIO1 gressively mechanically feeding it in -short intermittent movements through a forming and 'crimping die set, closing the forming and crimping die .set intermittently when the tubular blank is not being moved, and cutting off a formed section of the tube projecting from the die when another section is being formed.

3. The methodof claim 2 including heating a section of the tubular blank prior to entry through the die, when another portion of the-tubular blank is being formed in the die. j a

4. The method of forming a hollow article from metal tube stoekwhich consists in closing one end of the tube, applying gas under pressure to the interior thereof, cr-irnping the tube at a point spaced from the tube closure to confine pressurized gas therein, leaving between said closure and crimp a tube section to be formed, closing forming dies on said section for the forming thereof, venting the pressurized gas from the section While confined between the forming dies, opening the dies and removing the section therefrom, and cropping the crimped and closure parts of the section therefrom.

5. The method of forming a hollow'shaped article from hollow stock which consists in applying gas pressure to the interior of said stock, closing sets of spaced-apart crimping dies on the stock to crimp the stock and isolate a stock sect-ion therebetween which is filled with pressurized gas, closing a forming die set on said section while thecrimping dies engage the stock, forming a vent in the stock section while die-confined to vent pressurized gas therefrom, and openingthe crimping and forming dies and removing the stock section therefrom.

6. The method of claim 5 including the further step of cropping at least one of the crimped parts from said stock section;

7. The method of claim 5 wherein the step of forming a vent in the stock section comprises piercing the wall of the stock section.

8. The .method of claim 5 wherein the stepof closing sets of crimping dies flattens the walls. of the hollow stock into intimate contact with one another.

9. The method of making a hollow metallic blade of airfoil cross section which consists in closing one end-of a tubular workpiece, heating the workpiece locally a section thereof which is to enter a forming die, advancing the heated section of the closed .tu-be between forming dies, applying gaspressure to the inside of the workpiece from its open end, closing the forming dies upon said workpiece section, the first time near its closed end, concurrently pinching to substantial flatness the workpiece at eachend ofbthe workpiece section to hold gas pressure therein during forming die closure, relie i g as pressure 8V from the formed and pinched workpiece section, opening the forming die,'advan ci ng the die-formed and pinched, workpiece section out of said forming die, andjcutting off the formed section inwardly of the pinched-grands thereof. 7

10. The method-of making a hollow metallic article of flattened section from a tubular blank, which consists in flattening and pinching'a short portion of the blank to provide a closure, introducing pressurized gaswithin' the blank, flattening and pinchingaysecond short portion of the blank, spaced from the first portion, leavingtherebetween a gasfilled elongated tubular bl-ank'porrtion, placing the gas filled blank portion between forming dies and closing the dies on the gas tilled portion whereby to form the portion tot-he desired'section against thegas. pressure confined therein by said flattened portions, piercing the blank whileit is still confined between dies to'vent pressurized gas (therefrom, and separating the dies and removing the formed blank therefrom.

p 11. The method of forming a hollow section from metal tube stock'comprising the steps of feeding gas under pressure to one end of the tube; flattening parts of the tube so that the walls thereof are in tight contact, at spaced apart points, leaving therebetween a tubular section containing gas under pressure; die pressing said tubular section to desired form; relieving flattening pressure on said tube permitting the escape of gas; and cutting out, from the formed tubular stock,--the hollow section desired.

12. The method of forming :a hollow section from metalrtube stockcomprising the steps of feeding gas under pressure to one end .of tl1e tube;.-ilattening pants on the tube so that the walls, thereof are .in tight contact, at spaced apart points, leaving therebetween a tubular sect-ion containing, gas under pressure; die pressing said tubular section to desired form; cutting a ventfor the relief of gas pressure in the formed part of the-tube before relief of die pressure thereon; relieving :die pressure; removing the formed part of the tube and cutting from the tube the formed ,part thereof.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain -1 Sept. 8, 1947 

